<style>
    .item1 {
        background: LightSkyBlue;
        grid-area: header;
    }

    .item2 {
        background: LightSalmon;
        grid-area: advert;
    }

    .item3 {
        background: PaleTurquoise;
        grid-area: content;
    }

    .item4 {
        background: lightpink;
        grid-area: footer;
    }

    .container {
        font-size: 1.5em;
        min-height: 300px;
        width: 100%;
        background: LightGray;
        display: grid;
        grid-template-columns: 1fr;
        grid-template-rows: 50px auto 1fr auto;
        grid-gap: 10px;
        grid-template-areas:
            "header"
            "advert"
            "content"
            "footer";
    }

    @media (min-width: 300px){
        .container{
            grid-template-columns: auto 1fr;
            grid-template-rows: auto 1fr auto;
            grid-template-areas:
                "advert header"
                "advert content"
                "advert footer";
        }
    }

    @media (min-width: 400px){
        .container{
            /* 请修改本行以下的代码 */

            grid-template-areas:
                "header header"
                "advert content"
                "footer footer";

            /* 请修改本行以上的代码*/
        }
    }
</style>

<div class="container">
    <div class="item1">header</div>
    <div class="item2">advert</div>
    <div class="item3">content</div>
    <div class="item4">footer</div>
</div>